MXPA06010296A

MXPA06010296A - Foam insulation/shading system for transparent structures.

Info

Publication number: MXPA06010296A
Application number: MXPA06010296A
Authority: MX
Inventors: Dror Amar; Stephen A Vineberg
Original assignee: Sunarc Of Canada Inc
Priority date: 2004-03-09
Filing date: 2005-03-09
Publication date: 2007-04-23
Also published as: EP1723288A1; AU2005219474A1; WO2005085541A1; JP2007527964A; IL177983A0; US20070069411A1; EP1723288A4; CA2559094C; US7818924B2; EP1723288B1; IL177983A; CA2559094A1

Abstract

A periodically shieldable solar structure (10) comprises a cavity formed between a pair of light transmitting members (12). A foam insulation/shading system (14) is provided for periodically filling the cavity with degradable foam. The foam insulation/shading system (14) comprises a series of foam generators (28) mounted within the cavity and distributed therealong to provide multiple foam generating points therewithin. The foam generators (28) are operatively coupled to a source of pressurized air and a source of foaming solution.

Description

SYSTEM OF INSULATION / SHADING OF FOAM FOR TRANSPARENT STRUCTURES BACKGROUND OF THE INVENTION Field of the Invention: The present invention is generally related to foam generation systems used in the isolation and / or shading of transparent structures such as greenhouses, atriums, etc.

Description of the Prior Art Construction structures are known to have cavities formed between double-beam transmission ceilings or wall membranes to receive degradable or replaceable foam insulation. The roof or wall cavities can be periodically filled with degradable foam to provide shading or thermal insulation. However, when this is desired to let light through the building to take advantage of solar energy, the foam can be easily dissolved and removed from the cavities. Examples of such constructions can be found in U.S. Pat. No. 3,672,184 and No. 4,562,674. The foam generators used in the aforementioned patents to fill the cavities of the ceiling and wall with foam bubbles, essentially consist of a fan that sprays a soap solution on a screen at the entrance of cavities of the ceiling and the wall. A disadvantage of such a large fan system is that it is difficult to adapt to the existing structure. Such systems, in particular, require that the thickness in the cavity between the membranes be large enough to accommodate a fan generator. Also, the foam generator with this type of system can not be placed in any desired part. This creates additional difficulties for more complex structures used for roofing. Finally, large fan foam generators generate foam characterized by large bubbles and thus having a lower insulation value.

Brief Description of the Invention Therefore, it is an object of the present invention to provide a new foam generator arrangement to periodically shield the sun or insulate a structure from a transparent construction or other structure that transmits light. Therefore, according to a general aspect of the present invention, there is provided a periodically protected solar structure, comprising at least one cavity formed in the middle of a pair of light transmitting members, and an isolation system. foam shading to periodically fill said at least one cavity with degradable foam, said insulation / shading system comprising an air supply pipe connected to a source of low pressure air and spread along at least one said supply pipe of foam forming solution connected to a source of the foam solution and extending along at least one cavity, and a series of axially spaced apart foam generators mounted in at least said cavity and distributed along provide multiple discrete foam generating points within it, the foam generators being located in the portion s At the end of at least one cavity, the low pressure air and the foam solution being supplied separately to said foam generators through said air supply tube and said foaming solution supply tube, each foam generator has a body defining a chamber, the chamber has an exhaust provided with a screen, each foam generator further has an air inlet configured to provide a low pressure air flow from the air supply tube to the chamber and at least one Injector connected to the foaming solution tube for spraying the foaming solution on an interior surface of the screen in such a way that said foam is generated by low pressure air released through the screen. According to a further general aspect of the present invention, there is provided an insulation / shading system in combination with a transparent construction structure having at least one cavity formed in the middle of a pair of members that transmit light, the system comprises a source of air at low pressure, a source of solution foam, and a series of axially mounted foam generators in locations spaced in the upper end portion of the at least one cavity to provide discrete foam generating points therealong, each said generator comprising a hollow head member defining a volume internal and having a porous exit surface and at least one air inlet connected to a source of low pressure air to direct said air through said porous exit surface, and at least one injector connected to the source of foaming solution and arranged to spray the foaming solution on said porous exit surface. According to a foam generator for generating degradable insulation / shading foam inside a ceiling / wall cavity of a transparent building structure, the foam generator comprises a source of low pressure air, an upper member which transports the screen and having an air inlet adapted to be connected to the low pressure air source to direct air through the screen, and at least one injector mounted to said upper member at an angle towards a central axis of the upper member and adapted to be connected to a source of foaming solution for spraying the foaming solution on the screen independently of the air, the screen being substantially normal to said central axis. According to the still general aspect of the present invention, there is provided a method of filling a cavity with insulation / shading foam, comprising a) spraying the foaming solution on a screen, and b) letting the air flow at low pressure through of the screen to cause foam to fall from the screen into the cavity. According to the still general aspect of the present invention, there is provided a foam generating apparatus and a method which incorporates a mixing chamber, such as a Venturi-type pressure differential injector, compressed air, and pressurized liquid soap, to produce a high flow of relatively dry yet dynamic foam, which is slightly light and durable. The term "screen" is here required to cover any mesh material, interwoven or interspersed material that defines a porous network through which the foam can be generated.

BRIEF DESCRIPTION OF THE DRAWINGS The reference will now be made to the accompanying drawings, showing by way of illustration a preferred embodiment thereof, and in which: Fig. 1 is a schematic perspective view of a low pressure foam generation system used in the insulation and / or protection of greenhouses according to one embodiment of the present invention; Fig. 2 is a cross section of a Venturi injector of the low pressure foam generation system showing the inlet sides of the compressed air and the liquid surfactant mixture, as well as the mesh where the current foam bubbles are formed; Fig. 3 is a cross section of the low pressure foam generator according to a second embodiment of the present invention; Fig. 4 is a schematic cross-sectional view showing one of the low pressure foam generators mounted to an air supply tube axially extended and centrally through a roof cavity of a building structure; and Fig. 5 is a schematic side view of the distribution pipe installation shown in FIG. Four.

Description of Preferred Modalities As will be seen hereafter, the first embodiment of the present invention is generally directed to a low pressure foam generator to produce foam bubbles to periodically insulate or protect solar structures of many different types. The example shown in the Figures is supplied to a greenhouse. However, it is understood that the present invention could also be installed to other types of transparent structures, such as atriums, residential, commercial or industrial buildings to name a few. Now referring to Figure 1, there is shown a greenhouse 1 0 having a conventional skeletal framework including, among other things, a number of vertical support columns and horizontal transverse trusses. The greenhouse 10 has a double-layer cover membrane 12 stretched over the skeletal framework. The double-layer cover membrane 12 can be made from sheets of polyethylene or other materials such as polycarbonate, glass or other forms of plastic to form the skin of the greenhouse 1 0. The cavities of the roof and wall (not shown) defined between the inlet and outlet of the layers of the double-layer cover membrane 1 2 are connected to a low-pressure foam generation system 14 generally comprising two independent, automatically controlled, liquid and air supply systems 1 5 and 17, and a plurality of axially spaced foam generating assemblies 28. The distance between the foam assemblies 28 depends on the volume of the roof and wall cavities, as well as the weight of the walls, the amplitude of the roof, and the distance between them. the inner and outer layers of the double layer cover membrane 1 2. The liquid supplying system 1 7 generally comprises a foaming solution of reservoir 16, a pump 1 8 and a foam supply or supply line 20. The air supply system 1 5 generally comprises an air compressor 22 and a feeder or compressed air supply line 24. The tank 1 6 contains a foaming solution essentially consisting of a surfactant and water. The foaming solution may be provided in the form of the concentrated solution derived from a concentrated hydrolyzed protein base, as used in the fire foam technique. Although the preferred liquid is water, it is understood that other liquids compatible with the surfactant can also be used. As shown in Figure 2, each foam generator assembly 28, can generally comprise a Venturi injector 30 having a motor flow inlet 32, a suction or induced flow inlet 34, an injection chamber 36 and an ejection outlet 38. The motor flow inlet 32 is connected in a fluid flow of communication with the foaming solution supply line 20. The ejection outlet 38 is connected in a fluid flow of communication with a chamber 40 defining a 90 degree bend from the horizontal to the vertical and leading to a packed net manifold 42 positioned within a vertically oriented cylindrical head 44. The chamber 40 has an extreme conical distal portion of increasing cross section. The Venturi injector or the educator-type generator must be vertically oriented to ensure even distribution of the foaming solution and mixing of the air through the packed mesh collector. When the Venturi injector or the educator type generator is placed horizontally to the foaming solution, through gravity, tends to separate from the mixture of the foaming solution and air, resulting in uneven coverage of the packed mesh collector. This leads to an inefficient process where only a certain area of the mesh mesh collector mesh is being used for foam generation. In addition, the area of the packaged mesh collector that is not being exploited for foam generation provides an easy way for air to escape resulting in an inefficient use of pressurized air. In use, the compressed air and the foaming solution are independently fed into the foam generating assemblies 28 through supply pipes 24 and 20, respectively. The control valves 46 and 48 are respectively provided in the supply lines 20 and 24 to independently adjust the flow of the compressed air and the foaming solution. One of the valves in the supply line of the foaming solution 20 downstream of the pump 18 is a mechanical valve used for flow control and the second valve is an electric valve used to close or open line 20. The pump 18 is used to pump low pressure foaming solution towards the roof of the greenhouse 10 where the foam generating assemblies are located 28. The compressed air at a pressure of about 3 to about 10 PSI (measured at the compressor outlet) enters the compressed air. the inlet 32 of the eductor 30 where it is constricted to the injection chamber 36, and switches to an injection stream at a high speed. The increase in velocity through the injection chamber 36 results in a depression in the pressure, thus allowing the foaming solution (e.g., the mixture of water and surfactant) to be entrained through the induced flow inlet 34 and be dragged into the airstream. As this new mixture of compressed air and liquid soap is diffused towards the injector outlet 38, its speed is reduced and converted into pressure energy. This pressure is lower than the inlet pressure. The new combination of air and liquid is mixed in the combination chamber 40 before being forced through the mesh material, it is transformed into high quality foam (small bubble). It is important to note that in this application, the liquid can be pumped while maintaining a desired pressure in the liquid supply system 17. It is observed that using the foaming solution as the driving fluid would result in very moist dense foam, with a very low volume. Wet foam should be avoided in the application of insulation. A major advantage of the aforementioned system is that the foam is produced at a specific point, called the point of the mixture, which can be placed at any desired location. The compressed air and the pressurized foaming solution are transported independently of the mixing point by the air and liquid supply systems 15 and 17. This installation can be used as well for many types of structures, whose roofs are not formed uniformly, allowing a coverage complete of foam insulation. The quality of the foam should be characterized by the size of its bubbles, which can range from 1 to 5mm. The initial moisture of the foam is another characteristic. In this apparatus a desired quality of foam is produced by: 1) Control of the proportion of air or liquid, which can be adjusted by: a) the variation of the air flow and / or pressure entering the eductor 30 b) the variation of the liquid flow and / or pressure entering the suction inlet 34 c) the variation of both air and liquid 2) variation of the concentration of the surfactant in the liquid mixture from 2% to 10% 3) Use of different types and measures of packaged mesh The automatic control of the system is provided by a computerized control panel that controls the operation of the equipment and valves 46 and 48. From figure 3 to 5 a second embodiment of the present invention is shown where similar numerical references refer to similar parts. According to the second modality, each foam generator assembly 28 takes the form of a number of full-cone, wide-angle injectors 50 (two in the illustrated embodiment) mounted on a hollow upper member 52 preferably at an incident angle of 45 degrees towards a screen 42 Mounted to an outlet end of the upper member 52. Each injector 50 is connected in a fluid flow of communication to the foam liquid supply line 24. The upper member 52 has a central air inlet 54 at an opposite root thereof. to screen 42 '. The air inlet 54 is connected in fluid flow communication to the air supply line 24. As shown in Figure 4 and 5, the upper members 52 of the foam generator assemblies 28 'can be conveniently and directly mounted to supply line 24 at regular intervals throughout this. The air inlet 54 of each upper member 52 is preferably provided with an appropriate fit to allow assembly and disassembly thereof in the air supply line 24 within the roof / wall cavities of the building structure. As shown in FIG. 4, the air supply line 24 and the liquid foam supply line 20 both extend longitudinally centrally in the cavities of the roof 56 in the middle of an exit roof membrane 58 and a inlet roof membrane 60. The upper members 52 are longitudinally distributed along the air supply line 24 in the roof cavity 56 to provide multiple foam generator spots to periodically fill the same with degradable foam. Each upper member 52 has a large cylinder portion 62 and a frusto-conical portion 64 converging within a small cylindrical portion 66. The shield 42 'is mounted on the distal end of the cylindrical portion 66. The injectors 50 are mounted to the portion frustoconical 64 so as to lean to approximately 120 degrees. In the embodiment illustrated in Figure 3, the injectors 50 are at a distance of approximately 47mm from the screen 42 'and operate at a pressure with a variation between 20 and 30 psi. The injectors 50 are positioned and operate to maintain the full area of the continuously wet 42 'screen. The injectors 50 are of standard construction. The screen 42 'can be made from a 3 mm scouring cloth, such as wool used to wash the dishes. The air is fed to each upper member 52 at a low pressure of about 1 to 7 psi. The air flow of the upper members 52 is regulated by a fixed measuring orifice defined by the air inlet 54 of each upper member. In use, the liquid soap is sprayed onto the entire surface of the screen 42 'by the injectors 50. As the air is fed to the upper members 52 through the air inlets 54 thereof, it flows through the the screen 42 ', foam is generated. The moisture of the foam generated through the screen 42 'can be controlled by the flow of the injectors 50 and by the type of surfactant; varying the type of screen 42 'that can also influence the size of the bubble. As shown in Figures 4 and 5, a third pipe 68 is preferably also mounted within a roof cavity 56 to supply a series of fenders 70 with a washing liquid to periodically wash the roof membranes 58 and 60. The soap liquid resulting from the degradation of the bubbles in the cavity of the roof 56 can be advantageously recovered and used as washing liquid. Alternatively, the third pipe 68 can be connected to the water source. The fenders 70 are preferably evenly distributed to the upper part of the third pipe 68. The embodiments of the invention described above are intended to be exemplary. Accordingly, those skilled in the art will appreciate that the foregoing description is illustrative only, and that various alternatives and modifications may be foreseen. Accordingly, it is intended that the present encompass all such alternatives, modifications and variations which fall within the scope of the appended claims.

Claims

CLAIMS 1. A definable solar structure that can be periodically protected, characterized in that it comprises at least one cavity formed between a pair of membranes that transmit light, and a foam insulation / shading system to periodically fill at least one cavity with degradable foam, said insulation system / foam shading comprising an air supply pipe connected to a source of low pressure air and spread along said at least one cavity, a supply pipe of foaming solution connected to the source of the foaming solution and extended to the at least one cavity, and a plurality of axially spaced foam generators, mounted in at least said cavity and distributed along the same to provide multiple discrete foam generating points therein, the generators of foam being located in an upper end portion of the at least one cavity, the air at low pressure and the foaming solution being separately supplied to said foam generators through said air supply pipe and said foaming solution supply pipe, each of the foam generators having a body defining a chamber, the chamber having an outlet provided with a screen, each foam generator having an air inlet configured to provide a low pressure air flow from the air supply pipe to the chamber and at least one injector connected to the foam solution pipe to spray the Foaming solution on an internal surface of the screen in such a way that the foam is generated by the low pressure air released through the screen.
2. The solar structure according to claim 1, characterized in that the air inlet is centrally located with respect to the screen and in opposite front relation with respect thereto.
The solar structure according to claim 1, characterized in that at least one injector is mounted at an angle towards the central axis of each foam generator, the screen being substantially perpendicular to said central axis.
4. The solar structure according to claim 1, characterized in that said body has a cylindrical roof portion that is submerged within an intermediate frusto-conical portion terminating within a final cylindrical discharge portion, said cylindrical discharge end portion being of a transverse area greater than said cylindrical root portion, said screen being mounted on top of said cylindrical discharge end portion, said air inlet being provided through a lower surface of said cylindrical root portion, and said at least one injector mounted in said intermediate frusto-conical portion in an angled manner to said air inlet and said screen.
5. A foam insulation / shading system in combination with a transparent construction structure having at least one cavity formed between the pair of membranes that transmit light, the system comprises a source of low pressure air, a source of foaming solution, and a plurality of foam generators mounted in axially spaced locations along an upper end portion of the at least one cavity so as to provide discrete foam generation points therethrough, each said foam generator comprising a hollow upper member defining an internal volume and having a porous exit surface and an air inlet connected to the low pressure air source to direct air through said porous exit surface, and at least one injector connected to the source of foaming solution and adapted to spray the foaming solution on said porous exit surface.
The combination according to claim 5, characterized in that the source of air at low pressure includes an air supply pipe, and wherein said air inlet of each foam generator is connected to said air feed pipe.
The combination according to claim 5, wherein said upper membrane has a roof portion that becomes an intermediate widening portion that terminates at a discharge end portion, said discharge end portion having a larger cross-sectional area than said roof portion, said porous outlet surface being provided at a distal end of said end discharge portion, said air inlet being provided through a lower portion of said roof portion, and wherein at least one injector is mounted thereon. spreading portion angularly to said air inlet and said screen.
8. A foam generator for generating a degradable insulation / shading foam inside a ceiling / wall cavity of a transparent building structure, the foam generator comprising a low pressure air source, an upper member having a screen and having an air inlet adapted to be connected to the low pressure air source to direct air through the screen, and at least one injector mounted on said upper member at an angle toward the central axis of the upper member and adapted to be connected to a source of foaming solution for spraying the foaming solution on the screen independently of the air, the screen being substantially normal towards said central axis.
9. A method of filling a cavity with insulation foam / shading, characterized in that it comprises: a) spraying a foaming solution on the screen, and b) flowing the air at low pressure through the screen to cause the foam to fall from the screen to inside the cavity.
10. A method according to claim 10, characterized in that the air is supplied between 1 to 7psi. eleven .
A method according to claim 10, characterized in that the foaming solution is supplied at a minimum of 20psi.
12. A method according to claim 9, characterized in that it comprises performing steps a) and b) in various locations along the cavity.
A method according to claim 12, characterized in that said locations are provided in an upper end section of the cavity.
The foam insulation / shading system according to claim 1, characterized in that a control valve is provided in said supply line of foaming solution downstream of said pump.
15. A foam insulation / shading system for periodically protecting a transparent construction structure, the system comprises a source of compressed air, a source of foaming solution, and series of foam generators, each said foam generator comprising an upper member hollow defining an internal volume and having a porous exit surface and an air inlet connected to the source of compressed air to direct the air through said porous exit surface, and at least one injector connected to the source of foaming solution and adapted to spray the foaming solution on said porous exit surface.
The foam insulation / shading system according to claim 15, characterized in that - the compressed air source includes an air supply pipe, and wherein said air inlet of each said foam generator is connected to said supply pipe of air.
The foam insulation / shading system according to claim 15, characterized in that said upper membrane has a roof portion that becomes an intermediate widened portion terminating at a discharge end portion, said porous exit surface being provided at a distal end of said discharge end portion, said air outlet provided through a lower portion of said roof portion, and wherein at least two injectors are mounted to said intermediate expansion portion angularly to said air inlet and said screen.
18. A foam generator for generating a degradable foam within a ceiling / wall cavity of the structure of a transparent building structure, the foam generator comprising an upper member containing a screen and having an air inlet adapted to be connected to a source of pressurized air to direct air through the screen, and at least one injector mounted on said upper member and adapted to be connected to a source of foaming solution for spraying the foaming solution on the screen.